Police found cannabis and tobacco worth an estimated £1m when officers raided Gibbett Site Pig Farm on Hale Road in Bradenham on November 24.

Seven people were initially arrested following that discovery, and earlier today another two were detained by Norfolk Constabulary’s Tactical Crime Team in connection with the investigation.

The two men, one aged in his 50s from the Ipswich area and one aged in his 30s from the Sudbury area, were arrested on suspicion of money laundering, cultivation of cannabis and being concerned in the supply of Class B drugs. A police spokesman said they remain in custody.

Of the seven earlier arrests, two men, a 37-year-old and a 35-year-old, were subsequently released and will face no further action.

A 30-year-old man and a 47-year-old man will remain on police bail until July 17.

A further three people – a 31-year-old man, and a 20-year-old man, and a 45-year-old woman – are all Chinese nationals and their cases are still being dealt with by the Home Office.

Following the discovery, Norfolk police said the operation at Bradenham was the largest cannabis factory they had seen in recent years, and described it as a “highly organised and sophisticated operation”.

They found a production operation growing hundreds of cannabis plants, and a second farm building containing 200 large sacks, each weighing about 20kg, of raw tobacco and a crude shredding machine to produce hand-rolling tobacco.

Officials from Her Majesty’s Revenue and Customs said the tobacco – which weighed some four tonnes – would be worth more than £1m alone.